Apparatus and method for ground related positioning of an elevator on an earth scraper

ABSTRACT

An elevator located at the open end of a scraper bowl is rotatable upon a pivot connection of the upper end of the elevator to the bowl. A pair of transversely spaced brackets on the elevator and extending toward a draft frame of the scraper has a cam surface on the underside of each bracket. The draft frame has a support member extension positioned under each cam surface. A pair of levers is connected to the draft frame at one end and at the other end normally contacts the cam surface of the bracket. A rubber spring is located between each support member and lever. The scraper blade at the lower open end of the bowl is set at the desired digging depth by rotating the blade about the horizontal axis of the rear support wheels of the scraper in a conventional manner. The position of the lower end of the elevator relative to the ground will remain unchanged during rotation of the blade because the elevator is supported upon the non-rotated draft frame and counter-rotated at the elevator pivot. Rotation of the draft frame about the horizontal axis of its support wheels will change position of the contact surface of each lever upon the cam surface of each bracket. The bracket cam surface is shaped or oriented so that any vertical change in the position of the draft frame at the elevator will be nullified by an identical vertical counter positioning of the elevator. Thus, the elevator will remain at the original position relative to the ground and will be positioned increasingly forward of the blade for increasing digging depths. The rubber spring reduces shocks upon the elevator.

United States Patent 191 Hyler et al.

[451 Apr. 30, 1974 [75] Inventors: John H. Hyler; Clifford E. Johnson;

Dale 0. Freeburg, all of Peoria, 111.

[73] Assignee: Westinghouse Air Brake Company,

Peoria, 111.

[22] Filed: Aug. 4, 1972 [21] Appl. No.: 278,152

[52] U.S. Cl 37/8, 37/195, 198/117, 214/8326 [51] Int. Cl B60p 1/36 [58] Field of Search 37/8, 195; 198/117, 118; 214/8326 [56] References Cited UNITED STATES PATENTS 3,334,428 8/1967 Rezabek 37/8 3,048,934 8/1962 Hancock 37/8 3,700,383 10/1972 Boersma 37/8 3,210,868 10/1965 Liess 37/8 3,452,458 7/1969 Campbell et al 37/8 3,427,641 2/1969 Duke 37/8 Primary Examiner-Robert E. Pulfrey Assistant Examiner-Eugene l-l. Eickholt Attorney, Agent, or Firm-Frank Wattles [57] ABSTRACT An elevator located at the open end of a scraper bowl is rotatable upon a pivot connection of the upper end of the elevator to the bowl. A pair of transversely spaced brackets on the elevator and extending toward a draft frame of the scraper has a cam surface on the underside of each bracket. The draft frame has a support member extension positioned under each cam surface. A pair of levers is connected to the draft frame at one end and at the other end normally contacts the cam surface of the bracket. A rubber spring is located between each support member and lever.

The scraper blade at the lower open end of the bowl is set at the desired digging depth by rotating the blade about the horizontal axis of the rear support wheels of the scraper in a conventional manner. The position of the lower end of the elevator relative to the ground will remain unchanged during rotation of the blade because the elevator is supported upon the non-rotated draft frame and counter-rotated at the elevator pivot. Rotation of thedraft frame about the horizontal axis of its support wheels will change position of the contact surface of each lever upon the cam surface of each bracket. The bracket cam surface is shaped or oriented so that any vertical change in the position of the draft frame at the elevator will be nullified by an identical vertical counter positioning of the elevator. Thus, the elevator will remain at the original position relative to the ground and will be positioned increasingly forward of the blade for increasing digging depths. The rubber spring reduces shocks upon the elevator.

13 Claims, 7 Drawing Figures PATENTEUAPR 30 m4 7 5807.063

SHEET 3 [1F 3 APPARATUS AND METHOD FOR GROUND RELATED POSITIONING OF AN ELEVATOR ON AN EARTH SCRAPER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to an earth-working scraper having an endless conveyor or elevator for moving material into the scraper bowl, and specifically to such a scraper having means for maintaining the elevator at a selected distance above the ground.

2. Description of the Prior Art In the conventional earth scraper which includes an endless conveyor or elevator for assisting in the loading of the scraper bowl, the elevator is usually pivot mounted or link mounted at its upper end onto the bowl structure and has its lower end disposed above the cutting blade of the scraper at the forward open end of the bowl structure. In a structure of this type it is desirable that the lower end of the elevator be permitted to rise and descend to accommodate the various quantities of material and sizes of objects which may enter into the scraper bowl during the digging operation.

The rate at which material may be loaded into the bowl is affected by the depth of cut. The lower end of the elevator must be at a suitable distance above the ground and in position to have its flights sweep the disturbed earth into the bowl. conventionally, the relative position of the lower end of the elevator with respect to the cutting blade is set by limiting stops. The elevator is supported upon the bowl structure and its weight forces it against a lower stop located on the bowl. To adjust the blade-elevator relative position, the stop may be manually repositioned, as for example byplacing shims under the stop to elevate it, or other means for elevating the stop. To increase the space between the elevator and cutting blade, the lowest point of the elevator must shift upward or upward and rearward with reference to the cutting blade.

To permit relatively large objects, e.g., boulders, to enter into the bowl, the elevator must be raised or permitted to rise vertically. Conventionally, to permit the elevator to be raised and lowered to provide large blade-elevator separation and entry of large objects, the elevator is hinged at its upper connections to the bowl. The elevator moves upon a pair of links, each link with two pivots so that the elevator can be forced vertically upward. Thus, the lower end of the elevator may be forced upward by the material or objects or powered upon a crane linkage.

One disadvantage of conventional devices is that'they have at most only one proper setting for digging a selected soil. Advance of a cutting blade at a certain depth will produce a shear plane dividing disturbed soil from undisturbed soil. The angle of shear plane depends upon the soil conditions. The elevator should be positioned so that the tips of its flights will pass tangentially to the ground surface at a point slightly forward of the intersection of the shear plane with the ground surface. .In this position the flights will not strike undisinto the bowl. Upon adjusting the dig depth or encountering a modified soil condition, it becomes necessary to change the position of the elevator to obtain optimum operation. A deeper cut in unchanged soil requires the elevator be moved vertically and horizontally forward. A change in soil conditions may require a similar adjustment. Conventional devices can only reposition the lower end of the elevator vertically or vertically and horizontally rearward along the longitudinal axis of the inclined elevator. Thus, a proper adjustment cannot be made and compromises in operation become necessary. The flights may be caused to strike undisturbed soil producing loss of power and increased wear, tear and breakage. On the other hand the flights may be positioned too far above the ground so that disturbed soil is not swept into the bowl and maintained there. Furthermore, any adjustments must be made manually by repositioning the limiting stops.

The following patents are representative of conventional devices:

Patent No.

3,270,443 Earth Scraper with Self-Loading End- 'less Conveyor 3,191,322 Earth Scraper with Pivoted Conveyor 3,048,934 Conveyor Mounting for Elevating Scraper The present invention avoids the shortcomings of the conventional devices. The elevator is supported upon the draft frame. When the cutting blade and bowl are rotated about the rear wheels to lower the blade, the elevator pivots upon the bowl but does not move vertically relative to the ground. The elevator is supported upon a cam surface so that rotation of the draft frame about the front wheels will reposition the surface to au tomatically adjust the position of the elevator at its original distance from the ground. The rotation of the cutting blade to a greater depth will increase the vertical and horizontal distance between the blade and lowest point of the elevator, thus achieving the desired forward repositioning of the lower elevator relative to the blade.

A further advantage of the present invention is the shock cushion provided by a spring upon which the elevator is supported.

These and other advantages will become evident upon a reading of the detailed description of the invention.

SUMMARY OF THE INVENTION Briefly, the invention provides a self-loading scraper comprising conventional ground wheels and an open end bowl supported on the wheels. A scraper blade is supported by the bowl adjacent its open end. A pair of draft members connect a draft frame to the bowl. The draft members are supported at one end onto the draft frame and at the other end are pivotally connected to the bowl. Means are provided for raising and lowering the scraper blade by rotating the bowl upon the wheels. An inclined endless conveyor is positioned at the open end of the bowl with transversely spaced sides and a lower end in proximity to the scraper blade for conveying material into the bowl.

The improvement of the invention adds to the conventional elements to further comprise a pair of conveyor members at one end pivotally connected to the bowl in the proximity of the upper open end of the bowl and at the other end secured to the upper ends of the sides of the conveyor. A means is provided for automatically maintaining the ground-lever related position of the lower end of the conveyor during raising and lowering of the scraper blade whereby the conveyor is rotated upon the pivot connection of the conveyor members and the lower end of the conveyor is movable relative to the scraper blade in a direction combining vertical and horizontal movement. Further provided is a means for reducing shock caused by movement of the conveyor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graphic representation of the scraper blade in relative position to the elevator for selected depths of soil cut and selected soil conditions.

FIG. 2 is an elevation view of a scraper with the elevator in a travel position.

FIG. 3 is a plan view of the scraper of FIG. 2.

FIG. 4 is an enlarged elevation view of a part of the scraper of FIG. 6.

FIG. 5 is an enlarged elevation view of another embodiment of the part illustrated in FIG. 4.

FIG. 6 is an elevation view of a scraper with the scraper blade at moderate soil depth and the elevator at a selected distance above the ground.

FIG. 7 is an elevation view of a scraper with the.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now particularly to FIG. 1, the optimum operating conditions are illustrated for a scraper blade and elevator at selected dig depths and for selected soil conditions. A scraper blade is illustrated at selected dig depths a, b, c for soil conditions having shear failure planes of 45, 30, 25 from horizontal. An elevator has a longitudinal axis or centerline d with the axis of rotation of a lower idler ate. Flights n, n, n are illustrated with their tips tangential to their respective ground surfaces b, a, c with the paths of the tips traced respectively at b, a,

At a depth b the flight n tangentially approaches surface b between the 45 shear plane and 30 shear plane. This lowest point of flight path is slightly forward of the intersection of the 45 shear plane with surface b. Optimum conditions exist for soil conditions producing a shear plane of 45 for a digging depth and vertical separation of blade mand flight n represented by b. Flight path b passes above ground intersection of the 30 shear plane. The flight n is unable to sweep all the disturbed ground and is inefficient with respect to the 30 shear plane. Furthermore, flight n is in a downward movement as it approaches the 30 intersection and can encounter a roll m of disturbed or slightly disturbed soil forward of the 30 intersection. The downward force of flight n will compress the roll m against supporting non-disturbed soil in the shaded region forward of the 30 shear plane and produce a shock or drag on flight n. For a 25 shear plane, flight n misses a substantial amount of disturbed soil.

At depth a, a shallower depth, the idler and flight n must be vertically adjusted to the position of flight n to have the flight tangentially approach the ground surface. After the vertical adjustment the optimum operation condition is not present for any of the soil condi- 4 tions. The tangential point appears too far forward of the 45 intersection and is slightly rearward of the 30 intersection; however, both of these soil conditions may be suitably compromised. Nevertheless, the adjustment for flight n is improper for a 25 shear plane and a forward horizontal adjustment would be necessary to suitably compromise for digging its soil.

For a dig depth b and a setting of the flight at n, the elevator may be damaged. The shaded areas forward of the 45 shear plane represent undisturbed soil struck by flight n. Similarly, undisturbed soil is struck forward of the 30 shear plane. The shock to the elevator caused by striking the undisturbed soil can cause expensive damage and should be avoided. An overcorrection to avoid damage can be represented by setting the flight at n or n. Neither flight paths b or 0' would produce adequate sweep of the disturbed soil.

For a depth c and a flight setting at n, some horizontal adjustment towards the 45 intersection can be effected as compared with a setting at n or n, but it becomes readily apparent that only by actually adjusting the lower idler and flight in a horizontal direction in addition to a vertical direction can an adequate selection of settings be made suitable to various dig depths and soil conditions. The desired vertical-horizontal adjustment of the elevator can be accomplished by moving the idler about a remote pivot near the upper end of the elevator (not shown in FIG. 1). The desired adjustment is done automatically in the scraper hereinafter described.

FIG. 2 and 3 illustrate a self-loading scraper generally designated by the reference character 10. The scraper 10 comprises a bowl 12 having bowl sides 13 and an open front designated at 14. The scraper bowl 12 at its open front 14 has connected thereto a transversely extending scraper blade 15 suitably secured to a bowl bottom 16. The rear end of the bowl 12 includes a movable ejector gate 17 suitably supported and guided by a structurally extending member 18. A rearwardly extending pusher structure is designated at 19 and includes a pusher block 20 conventional in the art. A fluid ram 21 is suitably connected to the ejector gate 17 for moving the same forwardly to dump material from the bowl and to retract the same to its original position. A rear axle structure is designated at 23 and is suitably supported on ground wheels 24 which are journalled on axles 25 supported on the members 18.

A draft structure generally designated at 26 includes a gooseneck structure 27 which has its forward end suitably connected to a conventionaltwo-wheel tractor and its rearward end is secured to a transversely extending torsion tube 28 having opposite ends connected to rearwardly extending side draft members 29 which, as indicated at 30, are pivotally connected to the bowl 12. A pair of hydraulic rams 31 are pivotally connected as indicated at 32 to the torsion tube 23, the rams 31 including extendable rods 33 pivotally connected as indicated at 34 to the bowl 12 of the scraper 10.

The scraper described is a conventional scraper with which the invention to be described forms a part. The description herein of the scraper and elements thereof is not intended to limit the scraper upon which the invention may be used. For example, the scraper blade 15 may be secured to a movable bottom 16 which may be separate from and supported by the bowl and allows variable positioning of blade 15 relative to the bowl l2.

Additionally, ejector gate 17 may be omitted together with its ancillary elements member 18, pusher 19, block 20, and ram 21, or other conventional means for evacuating the loaded material may be substituted. Also apparent is that any elevated supporting structure may be substituted for the draft frame 26 and gooseneck 27, and that the tractor need not be two-wheeled. The rams 31 and rods 33 are illustrative of more generally described means for raising and lowering the scraper blade.

The scraper includes an endless conveyor or elevator generally designated by the reference character at 35. The conveyor 35 comprises a frame 36 including a pair of horizontally spaced side plates 37 supporting at their upper ends a shaft 38 and at their lower ends a pair of stub shafts 39. The shaft 38 supports a pair of sprockets 40 and the shafts 39 support a pair of wheels 41. Endless chains 42 are trained about the sprockets 40 and wheels 41, the chains being connected to conventional conveyor flights 43. A pair of members or arms 44 are disposed on opposite sides of the conveyor 35, the arms 44 being rigidly connected to the side plates 47 by means ofbracket 45. The arms 44 are pivoted as indicated at 46 on the bowl 12 so that the conveyor with the arms 44 may be rotated upon pivot 46 as a unit, thus enabling a combination of vertical and horizontal movment of idler wheels 41. To achieve this direction of movement at the wheels 41, the pivots 46 should be located near the upper open end of the bowl so that the arms 44 are relatively short. Other conventional means for connecting the bowl and elevator to achieve the described movement at the lower end of the elevator are made apparent by this description and are included within the scope of this invention as equivalent structure. Torsional stiffeners (not shown) may be added to the arms to stiffen the movement of the arms 44 upon their pivotal mounts 46. The torsional stiffening of arms 44 at pivots 46 will maintain alignment of the elevator with the bowl sidewalls. Other means for stabilizing the arms 44 or maintaining alignment of the elevator are made apparent by this description and are within the scope of this invention.

As illustrated in FIG. 4, a pair of brackets 47 is mounted at the elevator 35 upon the side plates 37 extending toward draft frame 26 and gooseneck 27. Brackets 47 have undersides to provide cam surfaces 48. A pair of levers 49 is secured at one end to the frame 26 at 50. Contact surface 51 is provided at the end of each lever 49. Surfaces 51 normally contact surfaces 48. A pair of bracket support members 52 is integrally connected to draft frame 26 forming an extension thereof which at the free end is disposed immediately below lever 49. Rubber springs 53 are sandwiched between the bracket support members 52 and levers 49. Springs 53 may be made of any suitably resilient material which is capable of absorbing shocks to the heavy elevator. The surfaces of members 52 which are in contact with springs 53 are of a shape to maintain springs 53 upon members 52, or alternately springs 53 may be attached to members 52. Spacing means illustrated by shims 54 may be secured to the spring contacting surfaces of members 52. The addition of shims 54 will elevate brackets 47 and levers 49 and the lower end of the elevator at wheels 41 will be respositioned. Other spacing means may be substituted for the shims 54.

An alternate embodiment of the sub-combination illustrated in FIG. 4 is illustrated in FIG. 5. A pair of brackets 56 similar to brackets 47 is mounted at the elevator 35 upon the side plates 37 extending toward draft frame 26 and gooseneck 27. A pair of bracket support members 58 is integrally connected to the draft frame 26 forming an extension thereof which at the free end is disposed below the brackets 56. Rubber springs 60 are sandwiched between the bracket support members 58 and brackets 56, with one side 61 of each spring 60 secured to the underside surface of the corresponding bracket 56. The other side 62 of each spring 60 is adapted to slide upon the support surface of the corresponding member 58. Alternately, it is apparent that each spring side 62 may be secured to the support surface of the corresponding bracket 58 and the spring side 61 adapted to slide upon the underside surface of the corresponding bracket 56. Spacing means illustrated by shims 63 may be secured to the support surface or underside surface upon which the spring 60 is adapted to slide. The addition of the shims 63 will elevate brackets 58 and springs 60 and the lower end of the elevator at the wheels 41 will be repositioned. Other spacing means may be substituted for the shims In operation, FIG. 2 shows the scraper 10 in a travel attitude. Elevator 35 rests upon the load of earth in bowl 12. No weight of the elevator rests upon levers 49. The elevator 35 may be removed from supporting contact with draft frame 26. In FIG. 6, scraper 10 is illustrated in position to make a cut of moderate depth. Scraper blade 15 is lowered from the travel attitude to start digging. In lowering the blade 15, for example, by hydraulically operating the hydraulic bowl hoist cylinders and extending rods 33 of rams 31, bowl 12 is rotated with blade 15 about axles 25 of the rear wheels 24. In the embodiment illustrated in FIG. 4, elevator 35 rotates with the blade 15 to lower the blade until lever contact surfaces 51 are contacted stopping further rotation of the elevator. Further rotation or lowering of blade 15 causes the elevator to rotate in an opposite direction upon pivots 46 and the elevator is not further lowered. When blade 15 is at digging depth, the elevator 35 is supported on levers 49, members 52 and springs 53. The location of cam surfaces 48 of brackets 47 and contact surfaces 51 is predetermined to place the idler wheels 41 at a selected distance above the ground. The placement and shape of surfaces are an obvious choice of design which can be selected to produce the desired path of movement of the lower idler wheels.

In the embodiment illustrated in FIG. 5, the blade 15 is lowered by rotating elevator 35 as described until sides 62 of springs contact the corresponding members 58 and the springs 60 are compressed to assume a normal operation position for the digging depth. Further rotation of the blade 15 to obtain a different digging depth will rotate the elevator upon its pivots 46 and simultaneously the spring sides 62 will slide upon members 58 until a new normal operation position is assumed for the new digging depth, all without changing the elevation of the idler wheels 41. Springs 60 should have sufficient resiliency to overcome the shear stress in the spring and friction between the sides 62 and members 58 to permit sliding of the springs upon members 58 while supporting the weight of the elevator. As in the embodiment of FIG. 4, the location of bracket 56, members 58 and spring 60 is predetermined to place the idler wheels 41 at a selected distance above the ground. The placement and shape of sides 62 and members 58 are an obvious choice of design which can be selected to produce the desired path of movement of the idler wheels 41.

In FIG. 7, scraper 10 is illustrated in position to make a deep cut. Scraper blade is lowered below the position of FIG. 6 by further rotating the blade 15 about the axle as described. Elevator 35 rests upon the support member as illustrated by contact surfaces 51 and members 52 in the embodiment of FIG. 4 or the corresponding spring sides 62 and members 58 in the embodiment of FIG. 5. In adjusting the elevator from a moderate digging depth of FIG. 5 to the greater depth of FIG. 7, the lower idler wheels 41 maintain a constant distance above the ground. Rotation of blade 15 produces a corresponding counter rotation of the elevator at pivots 46. The blade 15 is moved vertically downward and rearward of the idler wheels 41. Thus it is apparent that the lower end of the elevator 35 is maintained at a constant distance above the ground for any depth of out within the range of movement of the contacting surfaces of FIG. 4, 5. For each change of depth, the idler wheels 41 will be adjusted vertically and horizontally relative to the blade 15.

In the event draft frame 26 and gooseneck 27 rotate about axle 65 of front wheels 66, for example, when the digging depth is changed, the distance of the elevator, above the ground will not change. In the embodiment of FIG. 4, support members 52 and levers 29 will advance contact surfaces 51 upon cam surfaces 48. A change in vertical position of contact surfaces 51 will be compensated due to the angle or shape of cam surfaces 48. Similarly, in the embodiment of FIG. 5, sides 62 will advance by sliding upon members 58 with the same resulting vertical compensation. The net result in both embodiments will be no vertical change of the elevator above the ground. It is evident no horizontal change will result. It is further evident that any combination of draft frame rotation or blade rotation as described will not ehange'the distance of the elevator above the ground.

To pass a large boulder into bowl 12, the elevator 35 would be forced upward by the boulder. In the embodiment of FIG. 4, the brackets 47 would be forced above and out of contact with levers 49. The lower end of the elevator would be rotated upon pivots 46 so the lower end moved upward and forward. After the boulder passed, elevator 35 would fall with brackets 47 falling upon contact surfaces 51. Spring 53 would absorb practically all of the shock energy. Other shocks would be absorbed and dissipated in the same manner. For equipment and operations not concerned with shock damage, springs 53 and members 52 can be omitted and levers 49 are retained to provide a contact surface and supporting member. In the embodiment of FIG. 5, the spring sides 62 are forced above and out of contact with members 58. The lower end of the elevator is rotated by the force of the boulder and the elevator is rotated upon pivots 46 in the same manner described for the embodiment of FIG. 4. After the boulder passes, the elevator falls on springs 60 and members 58. The shock energy is absorbed in a similar manner as described for the embodiment of FIG. 4.

It can be seen, therefore, that an improved elevator positioning device and method have been herein described. Modifications of this invention are made apparent by this disclosure. Those modifications, some of which are recited in this description, are within the scope of this invention and as set forth in the claims.

We claim:

1. A self-loading scraper comprising:

ground wheels;

an open end bowl supported on the wheels;

a scraper blade supported by the bowl adjacent its open end;

a draft frame;

a pair of draft members at one end supported on the draft frame and at the other end pivotally connected to the bowl;

means connected intermediate the bowl and the draft frame for raising and lowering the scraper blade by rotating the bowl upon the wheels;

an inclined endless conveyor positioned at the open end of the bowl and having transversely spaced sides and a lower end in proximity to the scraper blade for conveying material into the bowl;

a pair of conveyor members at one end pivotally connected to the bowl in the proximity of the upper open end of the bowl and at the other end secured to the upper ends of the sides of the conveyor;

means connected intermediate the conveyor and the draft frame for automatically maintaining the ground-level-related position of the lower end of the conveyor during raising or lowering of the scraper blade for digging whereby the conveyor is rotated upon the pivot connection of the conveyor members and the lower end of the conveyor is movable relative to the scraper blade in a direction combining vertical and horizontal movement; and

means for reducing shock caused by movement of the conveyor.

2. A self-loading scraper as recited in claim 1 wherein the means for maintaining the ground-related position of the lower end of the conveyor comprises:

a pair of brackets mounted upon the conveyor and extending toward the draft frame, said brackets having undersides'to provide cam surfaces;

a pair of levers secured at one end to the draft frame and each lever including a surface at its other end having a portion of which normally contacts the cam surface of each bracket; and

a pair of bracket support members integral with the draft frame and extending immediately below the levers and adapted to support the contact end of the levers.

3. A self-loading scraper as recited in claim 1 wherein the means for maintaining the ground-related position of the lower end of the conveyor comprises:

a pair of brackets mounted upon the conveyor and extending toward the draft frame, said brackets having undersides;

a pair of bracket support members integral with the draft frame and extending below the extended ends of the brackets; and

a pair of springs sandwiched between the bracket support members and brackets.

4. A self-loading scraper as recited in claim 2 wherein the means for reducing shock comprises:

springs sandwiched between the bracket support members and levers.

5. A self-loading scraper as recited in claim 3 wherein the bracket support members have cam surfaces and wherein the springs are secured to the brackets undersides and are slidably mounted upon the cam surfaces of the bracket support members.

6. A self-loading scraper as recited in claim 3 wherein the brackets undersides include cam surfaces and wherein the springs are secured to the bracket support members and are in slidable contact with the cam surfaces of the brackets undersides.

7. A self-loading scraper as recited in claim 5 wherein the springs are rubber springs.

8. A self-loading scraper as recited in claim 7 wherein the means for raising and lowering the scraper blade comprises:

a laterally spaced pair of bowl hoist cylinders connected to the bowl and draft frame; and

means for operating the bowl hoist cylinders.

9. A self-loading scraper as recited in claim 8 wherein:

the draft frame comprises a rearward end with a transverse extending tube formed thereon; and each one end of the draft members are supported on opposite ends of the transverse tube.

10. A self-loading scraper as recited in claim 9 wherein the bowl hoist cylinders are hydraulic cylinders and wherein the operating means include hydraulic pressure means. i

11. A self-loading scraper as recited in claim 10 and further comprising means for stabilizing the pair of upper conveyor members and maintaining alignment of the conveyor with the bowl sidewalls by torsionally stiffening the movement of said conveyor members upon their pivotal mounts.

12. A self-loading scraper as recited in claim 11 and further comprising spacing means secured upon the cam surfaces of the bracket support members for adjusting the position of the cams and conveyor supported thereon.

13. A method of positioning the lower end of the selfloading endless conveyor of an earth scraper in proximity to the scraper blade and at substantially constant distance above the ground-level for different digging depths, which comprises the steps of:

advancing the scraper along ground-level; and

automatically and simultaneously rotating the scraper blade about the axis of the rear support wheels of the advancing scraper while moving in an equal and opposite direction the lower end of the conveyor. 

1. A self-loading scraper comprising: ground wheels; an open end bowl supported on the wheels; a scraper blade supported by the bowl adjacent its open end; a draft frame; a pair of draft members at one end supported on the draft frame and at the other end pivotally connected to the bowl; means connected intermediate the bowl and the draft frame for raising and lowering the scraper blade by rotating the bowl upon the wheels; an inclined endless conveyor positioned at the open end of the bowl and having transversely spaced sides and a lower end in proximity to the scraper blade for conveying material into the bowl; a pair of conveyor members at one end pivotally connected to the bowl in the proximity of the upper open end of the bowl and at the other end secured to the upper ends of the sides of the conveyor; means connected intermediate the conveyor and the draft frame for automatically maintaining the ground-level-related position of the lower end of the conveyor during raising or lowering of the scraper blade for digging whereby the conveyor is rotated upon the pivot connection of the conveyOr members and the lower end of the conveyor is movable relative to the scraper blade in a direction combining vertical and horizontal movement; and means for reducing shock caused by movement of the conveyor.
 2. A self-loading scraper as recited in claim 1 wherein the means for maintaining the ground-related position of the lower end of the conveyor comprises: a pair of brackets mounted upon the conveyor and extending toward the draft frame, said brackets having undersides to provide cam surfaces; a pair of levers secured at one end to the draft frame and each lever including a surface at its other end having a portion of which normally contacts the cam surface of each bracket; and a pair of bracket support members integral with the draft frame and extending immediately below the levers and adapted to support the contact end of the levers.
 3. A self-loading scraper as recited in claim 1 wherein the means for maintaining the ground-related position of the lower end of the conveyor comprises: a pair of brackets mounted upon the conveyor and extending toward the draft frame, said brackets having undersides; a pair of bracket support members integral with the draft frame and extending below the extended ends of the brackets; and a pair of springs sandwiched between the bracket support members and brackets.
 4. A self-loading scraper as recited in claim 2 wherein the means for reducing shock comprises: springs sandwiched between the bracket support members and levers.
 5. A self-loading scraper as recited in claim 3 wherein the bracket support members have cam surfaces and wherein the springs are secured to the brackets undersides and are slidably mounted upon the cam surfaces of the bracket support members.
 6. A self-loading scraper as recited in claim 3 wherein the brackets undersides include cam surfaces and wherein the springs are secured to the bracket support members and are in slidable contact with the cam surfaces of the brackets undersides.
 7. A self-loading scraper as recited in claim 5 wherein the springs are rubber springs.
 8. A self-loading scraper as recited in claim 7 wherein the means for raising and lowering the scraper blade comprises: a laterally spaced pair of bowl hoist cylinders connected to the bowl and draft frame; and means for operating the bowl hoist cylinders.
 9. A self-loading scraper as recited in claim 8 wherein: the draft frame comprises a rearward end with a transverse extending tube formed thereon; and each one end of the draft members are supported on opposite ends of the transverse tube.
 10. A self-loading scraper as recited in claim 9 wherein the bowl hoist cylinders are hydraulic cylinders and wherein the operating means include hydraulic pressure means.
 11. A self-loading scraper as recited in claim 10 and further comprising means for stabilizing the pair of upper conveyor members and maintaining alignment of the conveyor with the bowl sidewalls by torsionally stiffening the movement of said conveyor members upon their pivotal mounts.
 12. A self-loading scraper as recited in claim 11 and further comprising spacing means secured upon the cam surfaces of the bracket support members for adjusting the position of the cams and conveyor supported thereon.
 13. A method of positioning the lower end of the self-loading endless conveyor of an earth scraper in proximity to the scraper blade and at substantially constant distance above the ground-level for different digging depths, which comprises the steps of: advancing the scraper along ground-level; and automatically and simultaneously rotating the scraper blade about the axis of the rear support wheels of the advancing scraper while moving in an equal and opposite direction the lower end of the conveyor. 